They can be disciplined, suspended or dismissed for not paying their debts according to the regulations; financial difficulties may make them more vulnerable to corruption by the criminals they are investigating; and if they happen to be undercover cops, their cover is blown if their creditors bring them to the High Court, where they will be publicly named and shamed.

As a young rookie garda, John [not his real name] never thought of these doomsday scenarios when he and his partner took out two mortgages from a willing lender during the boom. Now he is one of a growing number of gardai in serious financial difficulty despite holding down a permanent, pensionable public sector job.

The detective, who is in his 30s, won't give his real name because of his work. Nor does he want his superiors to find out about his predicament – which is officially in breach of Garda regulations. He is one of 90 gardai and their partners who have approached the Irish Mortgage Holders Association for help in surmounting his massive debt problem in the past year.

John and his partner, also a public sector worker, bought a house 10 years ago in a Dublin suburb for €250,000. But their financial troubles started four years later when the couple decided they wanted to transfer out of Dublin. In a decision they now regret, they bought their dream house in the West before John's transfer application had been submitted, believing it to be a "bargain".

"It was never meant to be an investment house. It was the family home that we planned to move to," John told the Sunday Independent. "We had no trouble getting finance," he said. "We borrowed from two Garda credit unions for the deposit on the house."

They borrowed €360,000 and rented out the house while John considered a transfer. Things didn't turn out as planned. By 2009 the economy had turned, their work kept them in Dublin and their two children were settled.

"We kept renting the house which was on an interest-only mortgage at that stage," he said. "The rent was around €1,000 to €1,100 and the mortgage was €1500 to €1600. Gradually as things worsened, we couldn't pay the difference between the rent and the mortgage."

The couple got some relief when EBS agreed to reduce the mortgage repayment to match the rental income. But as the pay cuts, income levies and pension levies ate into their public sector salaries, John and his partner found that they were increasingly struggling to pay the bills. "We had to dip into the rent money to pay for things like car insurance and car tax," he said.

After five years of rising debt and falling incomes, John and his partner sought help last year. They hope to negotiate a deal with the EBS, which is part of the largely state-owned AIB. The West of Ireland property is being sold for €135,000. The EBS will pocket the proceeds but John and his partner will still have to shoulder the €200,000 lump of negative equity debt that remains.

"Whether it's €200,000 or €250,000, I just don't have it," said John. He is hoping that he can reach a deal with the EBS to write off a portion of the €200,000 so that he can make manageable monthly repayments on the remainder.

Ironically, while he's hopeful of reaching a deal with the bank, he is coming under serious pressure from his own garda credit union. St Raphael's Credit Union has threatened legal action over a debt of more than €10,000. That could raises the prospect of being named in court.

John hasn't told his senior officers about his difficulties.

"I had hundreds of sleepless nights over this, not knowing what to do or where to go. Not having any financial experience, or know-how to negotiate with banks. When it came to the point that we had to dip into the rent, we knew we had to do something," he said.

According to the Garda Disciplinary Regulations, incurring a debt, becoming bankrupt or seeking court protection is a disciplinary matter that could lead to suspension or dismissal. Justice Minister Alan Shatter has suggested gardai won't be penalised. But the Irish Mortgage Holders Organisation wrote to the Garda Commissioner last week to clarify the regulations.

The group is also examining whether the identities of debt-laden gardai working in sensitive areas should be protected by having insolvency proceedings heard in camera.